Perhaps you should try some spelling variations:
thanh trung » thanh tung
duong trong » dung trong
thieu sang » chieu sang, thieu khang, thieu quang
dien quang » diep quang, trien quang, lien quan
trung tuan » trung thanh, trung tam, tran tuan
duong cong » dung cong, luong cong, trong cong
tap toan » tap doan, tap quan, bai toan
toan cau » toan cao, toan ban, toan tap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu sang) or (dien quang)) - thanh trung tuan ((duong cong) OR (duong trong)) tap toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sang) OR (dien quang)) - thanh trung tuan ((duong cong) OR (duong trong)) tap toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) or (dien quang)) - thanh trung tuan ((duong cong) OR (duong trong)) tap toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) or (dien quang)) - thanh trung tuan ((duong cong) OR (duong trong)) tap toan cau*.